Arrangement for attaching and axially fixing a shaft in a component

ABSTRACT

An arrangement for attaching and axially fixing a shaft ( 1 ) in a component ( 2 ), in particular a housing wall. The axial fixing element is in the form of a swaged bead ( 5 ) that can be produced by wobble riveting.

This application claims priority from German patent application serial no. 10 2009 001 661.9 filed Mar. 19, 2009.

FIELD OF THE INVENTION

The invention concerns an arrangement for attaching and axially fixing a shaft in a component, a method for attaching and axially fixing the shaft in a component, and, a device for implementing the method.

BACKGROUND OF THE INVENTION

The attaching and axial fixing of a shaft in another component can involve various problems For example, the parts to be connected may be made from different materials and will then also have different thermal expansion coefficients, and in the case of some joints such as press fits this can cause problems. Moreover, a connection of this type should be as compact as possible, i.e. designed to take up as little structural space as possible under load. From that standpoint, for example flange joints are not suitable because of the additional space they require and their additional weight. Thus, joints are known which are produced by cold forming one of the two components to be joined.

From EP 1 476 261 B1 a method for connecting an aluminum pressure-diecast component to another part is known, the other part preferably being in the form of a sheet component of another material. The aluminum pressure diecasting has a collar which is deformed by rolling a rolling tool all round its circumference in such manner that the sheet component is clamped firmly to produce a connection with positive interlock between the two components. Alternatively it is proposed, instead of the deformation by the rolling tool, to use a riveting technique such as the wobble riveting process.

Wobble riveting is a known alternative to conventional riveting, in which the closing head of the rivet is formed by a riveting ram, also called the riveting die, in the direction of the rivet axis. The disadvantages of this are the relatively large force required and the noise. In the wobble riveting process the closing head of the rivet is deformed in part by a riveting die that undergoes a wobbling motion such that the working face at the end of the riveting die, the so-termed die face, can be flat so that a cone-shaped rivet closing head is produced. DE 10 2005 040 795 A1 describes a process of this type for wobble riveting and a riveting device for carrying out the wobble riveting process.

From DE 33 15 758 A1 a device for wobble riveting is known, in which the riveting ram undergoes a wobbling motion and has a recessed working or die face.

SUMMARY OF THE INVENTION

The purpose of the present invention is to design an attachment arrangement of the type mentioned at the beginning, in such manner that the joint produced is also suitable for parts made from different materials and therefore having different thermal expansion coefficients, in particular aluminum pressure diecast materials and steel, and is also of compact form. A further purpose of the invention is to provide a suitable method for attaching and axially fixing the shaft, and a device for implementing the method.

According to the invention, the shaft is fixed by a swaged bead formed, on the component that holds the shaft, by wobble riveting. In this way a positively-locking, compact joint is produced by cold-forming of the component, which is also unimpaired by different thermal expansions, on the one hand of the shaft and on the other hand of the component.

In a preferred embodiment the component is made from an aluminum material, in particular a casting alloy, i.e. as a sand casting or a pressure diecasting. The component can be in the form of a housing wall of a transmission housing, and the housing wall can be an additional, plate-shaped component or an integral part of the housing itself. By means of the wobble riveting process, which is carried out using a riveting die that undergoes a wobbling motion, the component made as a casting is deformed step by step at its periphery so that only relatively low deformation forces are required and the risk of fracturing or cracking the material is largely excluded.

In a further preferred embodiment the shaft, preferably made of steel, has a collar with a first axial abutment surface against which the swaged bead is axially supported.

In a further advantageous design, the collar has a second axial abutment surface and the cast component has a stepped bore with at least one shoulder, which is supported axially against the second abutment surface. In this way the shaft is positively fixed relative to the component in both axial directions.

In another advantageous design, the shaft can be in the form of a hollow shaft, in particular a transmission shaft.

In the method according to the invention the shaft, which has a collar, is inserted into the component which has at least a first shoulder, as far as the axial abutment. Then the outer, front-end rim of the stepped bore is deformed by a process similar to wobble riveting, to produce a bead, a so-termed swaged bead. The deformation process does not take place in a single step, but in a number of steps following one another around the circumference so that the force applied for the deformation and hence also the associated noise are relatively low. Thanks to the careful deformation of the material, there is no risk of fracturing or cracking the material.

According to the invention, the deformation tool is in the form of a riveting ram that undergoes a wobbling motion and thus rolls around the periphery of the component. Preferably, the riveting ram is of annular shape with a diameter adapted to fit the stepped bore or shaft diameter.

BRIEF DESCRIPTION OF THE DRAWINGS

An example embodiment of the invention is illustrated in the drawing and described in greater detail below. Further features and/or advantages can be understood from the description and/or from the drawing, which shows:

FIG. 1: An axial section through a hollow shaft fixed axially in a component, and

FIG. 2: A detail X from FIG. 1, shown on an enlarged scale

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a shaft made as a hollow shaft 1, which is held and axially fixed in a plate-shaped component 2. The component 2 is preferably a sand casting or a pressure diecasting made from an aluminum material. The component 2 can be a separate intermediate housing wall, or an integrated wall of a transmission housing, in which the hollow shaft 1, preferably a transmission shaft, is supported in the axial and radial directions. The hollow shaft 1 is preferably made of steel and therefore has a thermal expansion coefficient smaller (by about 50%) that that of the component 2 made from an aluminum material. The component 2 has a stepped bore 3 with a shoulder 3 a. The hollow shaft 1 has a collar 4 for its axial fixing in the component 2.

FIG. 2 shows a detail X of FIG. 1 on an enlarged scale, from which the axial fixing of the two components 1, 2 can be understood clearly. The collar 4 of the hollow shaft 1 has first and second axial abutment surfaces 4 a, 4 b. The hollow shaft 1 rests with its second axial abutment surface 4 b against the shoulder 3 a of the component 2 and is therefore fixed in one axial direction. The axial fixing in the other direction takes place by virtue of a swaged bead 5 produced by cold forming of the component 2 radially inward and axially against the first abutment surface 4 a. Thus, the swaged bead 5 rests snugly against the collar 4 of the hollow shaft 1. Consequently, the hollow shaft 1 is fixed relative to the component 2 in both axial directions. The swaged bead 5 has a front face 5 a which, relative to a flat surface 2 a of the component 2, is offset inward (to the right in the drawing). The amount of this offset in the axial direction is called the swaging depth t and characterizes the axial displacement of the cast material of the component 2.

The mounting and fixing of the hollow shaft 1 into the component 2 takes place in the steps described below: The hollow shaft 1 is inserted into the stepped bore 3 until its collar 4 comes up against the shoulder 3 a. Then, a forming tool designed as a riveting ram (not shown in the drawing) is placed against the end face 2 a of the component 2, i.e. applied in the axial direction. The riveting ram (not shown) can preferably be annular or sleeve-shaped and its diameter matches that of the circular annular surface of the end face 2 a to be deformed. For deformation, the riveting ram undergoes a wobbling motion known from the wobble riveting process and at the same time it is pushed in axially until the swaging depth t is reached. At the end of the forming process the material of the component 2 has been deformed axially as far as the flat surface 5 a and at the same time radially inward to form the surrounding swaged bead 5, leaving a radial gap relative to the shaft 1.

INDEXES

-   1 Hollow shaft -   2 Component -   2 a Flat surface -   3 Stepped bore -   4 Collar -   4 a First axial abutment surface -   4 b Second axial abutment surface -   5 Swaged bead -   5 a End face -   t Swaging depth 

1-9. (canceled)
 10. An arrangement for attaching and axially fixing a shaft (1) to a component (2), wherein an axial fixing element is in a form of a swaged bead (5) produced by wobble riveting.
 11. The attaching arrangement according to claim 10, wherein the shaft (1) is made from steel.
 12. The attaching arrangement according to claim 10, wherein the component (2) is made from aluminum.
 13. The attaching arrangement according to claim 10, wherein the shaft (1) has a collar (4) with a first axial abutment surface (4 a) and the swaged bead (5) is axially forced against the abutment surface (4 a).
 14. The attaching arrangement according to claim 13, wherein the collar (4) has a second axial abutment surface (4 b) and the component (2) has a stepped bore (3) with at least one shoulder (3 a) which is abuts against the second axial abutment surface (4 b).
 15. The attaching arrangement according to claim 10, wherein the component (2) is a cast plate for supporting the shaft (1) in a transmission housing.
 16. The attaching arrangement according to claim 10, wherein the shaft is a hollow shaft (1).
 17. A method of attaching and axially fixing a shaft (1) to a component (2) with an axial fixing element in the form of a swaged bead (5), the method comprising the steps of: inserting the shaft (1) into a stepped bore (3) of the component (2) as far as an axial abutment, and deforming a front rim (2 a) of the stepped bore (3) by a process similar to wobble riveting.
 18. A device for implementing a method of attaching and axially fixing a shaft (1) to a component (2) with an axial fixing element in the form of a swaged bead (5), the method comprising the steps of inserting the shaft (1) into a stepped bore (3) of the component (2) as far as an axial abutment, and deforming a front rim (2 a) of the stepped bore (3) by a process similar to wobble riveting, and the device comprising either an annular or a sleeve-shaped riveting ram that undergoes a wobbling motion. 